How to determine the DCS flow display status
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I have a question for the experts: Is the gas flow rate displayed on DCS the actual flow rate in m3 or Nm3? Apart from the difference in units, how can we determine whether it represents the volume under standard conditions?
Under normal circumstances, those with temperature and pressure compensation methods correspond to standard-condition flow rates; otherwise, it is the actual flow rate!
It’s hard to tell if one is not from this field. As mentioned above, those with temperature and pressure compensation generally refer to flow rates under standard conditions; however, such compensation can be performed in a DCS (which is the case in most situations), as well as in field instruments (with internal compensation modules) or flow computers (where the compensated value is then sent to the DCS). Of course, if the unit on the flowchart is Nm3/h, it is definitely under standard conditions.
It’s hard to tell if one is not from this field. As mentioned above, those with temperature and pressure compensation generally refer to flow rates under standard conditions; however, such compensation can be performed in a DCS (which is the case in most situations), as well as in field instruments (with internal compensation modules) or flow computers (where the compensated value is then sent to the DCS). Of course, if the unit on the flowchart is Nm3/h, it is definitely under standard conditions.
It depends on the settings on the field instruments or the data sheet to determine whether the gas flow rate displayed on the DCS is in m3 or Nm3; the DCS merely shows this value as part of the display
Since operating conditions are variable, most flowmeters display values in standard cubic units.